Log In with keypad and LCD on 8051 microcontroller

In this article we will discuss about how to take input from user as username/password and check it for logging in. We will be using lcd for display the input and the status of logging in or any error.

Here we are using following components:

• P89V51RD2 microcontroller for programming in keil
• 80C51 microcontroller for simulation in proteus
• LM016L as 16x2 character LCD
• 4x4 matrix keypad.

Steps involved in program are as follows:

1. First we will take input from user for username
2. if username is wrong then we will clear entered username from array and we will set flags to default.
3. if username is right then we will ask for password
4. if password is wrong then we will clear entered username and password and we will set all flags to default.
5. if password is right then we will display logged in screen.
6. during above process if reset key is pressed then everything will be set to default

For how to use 16x2 character LCD and how to use 4x4 matrix keyboard, click on the links.

Code:

 //header files  
 #include<reg51.h>  
 #include"lcd.h"  
 #include"kbd.h"  
 #include"delay.h"  
   
 //to store entered username and password  
 unsigned char username[8];  
 unsigned char password[8];  
   
 //opriginal username and password  
 unsigned char fixusername[8]={1,2,3,4,5,6,7,8},fixpassword[8]={8,7,6,5,4,3,2,1};  
   
 //character count and check flags  
 unsigned char useri=0, passi=0, userflag=0, passflag=0;  
   
 void process();  
 void checkuser();  
 void checkpass();  
 void print_on_LCD(unsigned char);  
   
 int main(void)  
 {  
      init_LCD();  
        
      wrcmd(0x80,0);  
      write_to_LCD("user:");  
        
      while(1)  
      {  
           process();  
      }  
 }  
   
 void process()  
 {  
      unsigned char key;  
        
      //check if any key is pressed  
      key=getkey();  
        
      switch(key)  
      {  
           case 1:  
                print_on_LCD(key);  
                break;  
           case 2:  
                print_on_LCD(key);  
                break;  
           case 3:  
                print_on_LCD(key);  
                break;  
           case 4:  
                print_on_LCD(key);  
                break;  
           case 5:  
                print_on_LCD(key);  
                break;  
           case 6:  
                print_on_LCD(key);  
                break;  
           case 7:  
                print_on_LCD(key);  
                break;  
           case 8:  
                print_on_LCD(key);  
                break;  
           case 9:  
                print_on_LCD(key);  
                break;  
           case 15:  
                  
                //reset button  
                wrcmd(0x01,0);  
                wrcmd(0x80,0);  
                write_to_LCD("user:");  
                useri=0;  
                userflag=0;  
                passi=0;  
                passflag=0;  
                break;  
           case 16:  
                //check username was correct  
                if(userflag==1)  
                {  
                     checkpass();  
                }  
                //checking username right now  
                else  
                {  
                     checkuser();  
                }  
                delay(100);  
                delay(100);  
                break;  
                  
      }  
        
 }  
   
 void checkuser()  
 {  
      unsigned char i;  
        
      //check username  
      for(i=0;i<8;i++)  
      {  
           if(username[i]!=fixusername[i])  
                break;  
      }  
        
      //if username is correct  
      if(i==8)  
      {  
           userflag=1;  
           wrcmd(0xc0,0);  
           write_to_LCD("pass:");  
      }  
        
      //if username was wrong  
      else  
      {  
           //reset entered username  
           for(i=0;i<8;i++)  
           {  
                username[i]=0;  
           }  
             
           wrcmd(0x01,0);  
           wrcmd(0x80,0);  
           write_to_LCD("wrong username");  
           delay(100);  
           delay(100);  
           delay(100);  
           delay(100);  
           delay(100);  
           wrcmd(0x01,0);  
           wrcmd(0x80,0);  
           write_to_LCD("user:");  
           useri=0;  
           userflag=0;  
      }  
 }       
   
 void checkpass()  
 {  
      unsigned char i;  
        
      //check password  
      for(i=0;i<8;i++)  
      {  
           if(password[i]!=fixpassword[i])  
                break;  
      }  
        
      //if password is correct  
      if(i==8)  
      {  
           passflag=1;  
           wrcmd(0x01,0);  
           wrcmd(0x80,0);  
           write_to_LCD("Logged In");  
           //clear entered username  
           for(i=0;i<8;i++)  
           {  
                username[i]=0;  
           }  
           userflag=0;  
      }  
        
      //if password is wrong  
      else  
      {  
             
           //reset entered username and password  
           for(i=0;i<8;i++)  
           {  
                password[i]=0;  
                username[i]=0;  
           }  
           wrcmd(0x01,0);  
           wrcmd(0x80,0);  
           write_to_LCD("wrong password");  
           delay(100);  
           delay(100);  
           delay(100);  
           delay(100);  
           delay(100);  
           wrcmd(0x01,0);  
           wrcmd(0x80,0);  
           write_to_LCD("user:");  
           useri=0;  
           passi=0;  
           userflag=0;  
           passflag=0;  
      }  
 }  
   
 void print_on_LCD(unsigned char key)  
 {  
      unsigned char temp;  
        
      //check if printing password  
      if(userflag==1)  
                {  
                     //check if 8 characters are already entered  
                     if(passi<8)  
                     {  
                          password[passi]=key;  
                          passi++;  
                          temp=key+48;  
                          write_to_LCD(&temp);  
                          delay(100);  
                          delay(100);  
                     }  
                }  
                //entering username  
                else  
                {  
                     //check if 8 characters are already entered  
                     if(useri<8)  
                     {  
                          username[useri]=key;  
                          useri++;  
                          temp=key+48;  
                          write_to_LCD(&temp);  
                          delay(100);  
                          delay(100);  
                     }  
                }  
 }  

Output:

• successful LogIn

• Wrong username

• Wrong password

Note: I am working on optimization of this code. If you have any suggestions for reducing code and data size of this code then comment below.

Program files, hex file and simulation file are at this link. click there to download and test.